Annuals 15-40 cm tall. Stems erect, angular, much branched; branches crowded, glabrous. Leaves sessile, linear to broadly lanceolate, 1.5-4.3 × 0.2-0.4 cm, base obtuse, apex acuminate, midvein abaxially and adaxially distinct. Inflorescences racemelike, usually in many-flowered panicles. Flowers 5merous. Pedicel spreading to erect, to 8 cm, angular, glabrous. Calyx tube 1-1.5 mm; lobes linear to linear-lanceolate, 0.8-2.2(-2.7) cm, apex acuminate, midvein distinct. Corolla pale blue, with dark blue lines, 2-3 cm in diam., tube 1-1.5 mm; lobes elliptic-lanceolate to elliptic, 1.5-2.5 cm, apex acuminate to obtuse. Nectary connate at base into a tube pointed outward, apex lamellate, margin lobed. Filaments 6-8 mm; anthers blue, narrowly ellipsoid, 3-4.5 mm. Ovary ensiform to obconic, 1.2-1.4 cm, apex triangular acute. Stigma lobes triangular, decurrent to base of ovary. Capsules narrowly ellipsoid to obovoid-ellipsoid, 1.5-2.5 cm. Seeds light brown, globose, 0.3-0.4 mm in diam.; seed coat smooth. Fl. and fr. Aug-Sep.